To guide a catheter to a desired treatment site introducers and guide wires are used. In the case of guide wires, the guide wire is positioned within the vessel near the treatment site and the catheter is fed over the guide wire. The catheter follows the path of the guide wire through the vasculature until a portion of the catheter, such as the distal tip, reaches the treatment site. In some examples, the catheter includes a dedicated guide wire lumen sized and shaped to slidably receive the guide wire. The guide wire lumen may be entirely isolated from the other features of the catheter, including instrument lumens, instruments and the like. The provision of the guide wire lumen requires an allotment of space in the catheter to accommodate a guide wire. Alternatively, the catheter can be made larger to accommodate both the guide wire lumen and the desired instruments and instrument lumens. Larger catheters can have difficulty navigating the tortuous vasculature of the body and in some cases are unable to reach a treatment site in smaller vessels because they are simply too large to fit within the vessels.
In other examples, the guide wire is fed through an instrument or delivery lumen thereby consolidating the functions of a guide wire lumen and an instrument lumen into a single passage. In many examples, instruments, tubes and the like are positioned within instrument lumens that provide a discontinuous surface related to the function or construction of the catheter. These discontinuous surfaces snag guide wires that are fed into the instrument lumens preventing further advancement of the guide wires. This difficulty is further aggravated with guide wires having curved features designed to navigate bends in the vasculature. The curved features easily catch on the discontinuous surfaces of the instrument lumen and interrupt the smooth delivery of the instrument through the catheter. Stated another way, the interruptions in the consolidated lumen easily snag and halt the desired advancement of a curved guide wire. Because of these difficulties, a solution is needed for smoother transport of guide wires and the like inside of catheters.